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Forces & Motion with Simple Machines


 

Summary:
The students will be able to sort simple machines according to an applied force –push or a pull.

Main Curriculum Tie:
Science - 3rd Grade
Standard 3 Objective 1

Demonstrate how forces cause changes in speed or direction of objects.

Materials:


Attachments

Background For Teachers:
Simple machines are a part of learning about forces and motion. Students do not have to be tested on the names of the different simple machines; however, they should learn that simple machines help make “work” easier. There are six simple machines:

  • the lever
  • the inclined plane
  • the wedge
  • the screw
  • the wheel and axle
  • the pulley

Simple machines have few or no moving parts. These machines use energy to work. Combining two or more simple machines results in a compound machine.

This unit on forces and motion can be more focused using and enduring understanding and essential questions. They are as follows:

Enduring Understanding: Forces cause changes in the speed or direction of the motion of an object. The greater the force, the greater the change in speed or direction.

Essential Questions:

What is a force?
How are the forces of pushing and pulling the same? How are they different?
What forces do simple machines have on other objects? (We will focus on this one for the lesson.)
What kinds of forces help move objects?
What effect does “weight” have on objects?
What happens when objects of different weights collide?
How do forces apply when playing different kinds of sports?
How would your life be different without forces?

Intended Learning Outcomes:
1. Use science process and thinking skills.
2. Communicate effectively using science language and reasoning.

Instructional Procedures:
Invitation to Learn:

Show several kitchen tools, such as melon baller, spatula, pancake turner, pizza cutter, potato peeler, can opener, wooden spoon, jar with lid, etc.

What do these objects have in common? How are they different? Today we are going to learn about simple machines and how they can make work easier.

Instructional Procedures:

Six Simple Machines:

There are six different simple machines. We are going to learn what they are and how they can make work easier.

Show pictures/examples of the six different kinds of simple machines. Pass out the Simple Machines and Work recording sheet for students to complete while learning about the six types of simple machines.

Show the simple machines and the activity for each. After the introduction, students will do the experiments and determine whether each uses a push or a pull and how they are all used to help make work easier.

  1. What tools would be considered levers? Why would they be a lever? When using a lever do we push, pull, or both? (both) How does it make work easier?

    A lever is a simple machine. A lever is a board or bar that rests on a turning point. This turning point is called the fulcrum. An object that a lever moves is called the load. The closer the object is to the fulcrum, the easier it is to move.

    Examples of levers:

    • Teeter totter/Seesaw
    • Spatula
    • Hammer
    • Wooden spoon
    • Pancake turner
    • a Hammer (when it is used to pull a nail out of a piece of wood)
    • Bottle opener
    • Crow bar

    Try this experiment!

    • Materials:

      wooden ruler, textbook, a a desktop

    • Procedure:

      Lay a ruler on your desk with part of it hanging over the edge. Place a textbook on the other end. Try to lift the book by pressing down on the part of the ruler that is sticking out. Repeat this procedure several times. Move the book closer to the edge by pulling on the ruler. Continue until the book is right at the table's edge.

    • Things to think about during the experiment:
      • What simple machine was used in this experiment?
      • Was it easier to lift the book with a short or long ruler?
      • Can you think of a time when you use a simple machine like this?
    • Conclusion:

      The ruler is a lever in this experiment. The edge of the table is the fulcrum, and the book is the load. It is easier to move an object like the book when the fulcrum is closer to the load.

  2. What tools would be considered inclined planes? When using an inclined plane do we push, a pull, or both? (push uphill, gravity downhill) How does it make work easier?

    An inclined plane is a simple machine. It is a flat surface that is higher on one end. You can use this machine to move an object to a lower or higher place. Inclined planes make the work of moving things easier. You need less energy and force to move objects with an inclined plane.

    Examples of inclined planes:

    • Ramp
    • Slanted road
    • Path up a hill
    • Slide
    • Skateboard park

    Try this experiment!

    Materials:

    Stack the books in one pile. Lean one book against the other to create an inclined plane. Place the sock of rice on the table. While holding the end of the rubber band, lift the sock of rice straight up to the top of your book stack. Use the ruler to measure the length of the rubber band. Now put the bag of rice at the bottom of the inclined plane and drag it to the top of the stack of books by pulling on the rubber band. When it is almost to the top, measure the length of the rubber band. You may use the spring scale to show how much work it is to pull the sock up the ramp. How much work is it to pull the sock straight up in the air? Or do drag the sock along the floor?

    Things to think about during this experiment:

    What simple machine reduces the length of the rubber band in this experiment?
    Why was the rubber band more stretched when the bag was lifted straight up into the air?
    What other inclined planes could be used in an experiment like this?

    Conclusion: (Read this after you try the experiment.)

    It took more work to move the bag of rice straight up into the air. This is why the rubber band was stretched farther. It takes less force to move the bag of rice up the inclined plane.

  3. What tools would be considered wedges? When using an wedge do we push, pull, or both? (push/pull if sawing motion) How does it make work easier?

    A wedge is a simple machine used to push two objects apart. A wedge is made up of two inclined planes. These planes meet and form a sharp edge. This edge can split things apart.

    You probably use a wedge at lunch every day. A fork is considered a wedge. A fork can be used to cut or split food apart. Can you think of another wedge you use to help you eat? (How about a knife?)

    Examples of wedges:

    • Melon baller
    • Potato peeler
    • Pizza cutter
    • Knives
    • Axes
    • Forks
    • Nails

    Try this experiment!

    Materials:

    nail, bolt, hammer, block of wood

    Procedure:

    Try to hammer the bolt into the block of wood. Think about why a bolt cannot be hammered into the wood. Compare the nail with the bolt. Now try to hammer the nail into the wood.

    Things to think about during this experiment:

    Why is the nail easier to hammer into the block of wood?
    What simple machine is a nail?
    Can you name some other simple machines with the same characteristics as a nail?

    Conclusion:

    The nail is a wedge, it is easier to hammer into the wood. There is a sharp edge on the nail because it has two inclined planes joined together. This lets the nail separate the wood.

  4. What tools would be considered screws? When using a screw, do we push, pull, or both? (push/pull) How does it make work easier?

    A screw is a simple machine that is made from another simple machine. It is actually an inclined plane that winds around itself. A screw has ridges and is not smooth like a nail. Some screws are used to lower and raise things. They are also used to hold objects together. Jars use simple machines to hold the lids on the top. When you turn the lid, it raises or lowers.

    Examples of screws?

    • Jar lid
    • Light bulb
    • Stool
    • Clamp
    • Jack
    • Wrench
    • Key Ring
    • Spiral staircase

    Try this experiment!

    Materials:

    Nine‐ inch paper square, pencil, tape, marker, tabletop

    Procedure:

    Cut the square in half to make a right triangle. Use the marker to outline the diagonal side of the triangle. Now place the paper face down on the table. Place the pencil on one of the short sides of the triangle. Wrap the pencil around the triangle. Use the tape to keep it in place.

    Things to think about during the experiment:

    What simple machine is the right triangle?
    What simple machine was created when you wrapped the pencil around the triangle?
    Name some other examples of this machine.

    Conclusion:

    You made a screw out of an inclined plane when you wrapped the triangle around the pencil.

  5. What is a wheel and axle? When using an wheel and axle, do we push, pull, or both? (push/pull ‐ both) How does it make work easier?

    The wheel and axle is another simple machine. The axle is a rod that goes through the wheel. This lets the wheel turn. It is easy to move things from place to place with wheels and axles.

    You have probably seen a wheel and axle on a car. The axle turns when you put force on the wheel. Can you think of a different place where you might find a wheel and axle on a car besides what you see in this picture? How about the steering wheel or radio dials?

    A wagon has wheels and axles. This simple machine makes it easier to move these items. You would have a lot more work to do if you didn't have a wagon to pull things in.

    Examples of Wheels and Axles:

    • Can opener
    • Clock
    • Cars
    • Roller Skate
    • Wagon
    • Door knob
    • Gears in watches, clocks, and bicycles

  6. What is a pulley? When using an pulley do we push, pull, or both? (pull) How does it make work easier?

    Pulley: This simple machine is made up of a wheel and a rope. The rope fits on the groove of the wheel. One part of the rope is attached to the load. When you pull on one side of the pulley, the wheel turns and the load will move. Pulleys let you move loads up, down, or sideways. Pulleys are good for moving objects to hard‐ to ‐reach places. It also makes the work of moving heavy loads a lot easier.

    A crane uses a pulley to move a heavy wrecking ball. Without the use of a pulley, the wrecking ball would be very hard to move.

    Examples of places where pulleys can be used:

    • Flag poles
    • Clothes lines
    • Sailboat
    • Blinds
    • Crane

    Try this experiment!

    Materials:

    1 pulley, 2 pieces of ¼” diameter nylon rope 1 yard long, spring scale

    Procedure:

    Place the rope in the pulley. Tie or tape a heavy book to one end of the rope. Place the spring scale on the other end of the rope.

    Things to think about during the experiment:

    How much work is it to pull the book up to the top of the pulley?
    How much work it is to pull the book straight up without the pulley?

    • Name some examples of this machine.

    Conclusion:You used a pulley to lift a heavy load. What other loads might be easier to lift if you used a pulley?

Lesson and Activity Time Schedule:

  • Lesson is 35 minutes.
  • Activity experiments is 55 minutes.
  • Total lesson and activity time is 90 minutes.

Activity Connected to Lesson:

  1. Students work in small groups and move through the 5 simple machine activities. Pushes and pulls will be determined and students will decide how each simple machine makes work easier.
  2. Copy Simple Machine Cards: Examples of Levers, Examples of Inclined Planes, Examples of Wedges, Examples of Pulleys, Examples of Screws, and Examples of Wheels and Axles onto the same colored cardstock. Cut each card set vertically into four sets of three. Take 3 cards from each of the six sets and place into one set (this will make 4 sets). Students will work in small groups to determine which cards represent which simple machine and sort the cards.
  3. Next, students will apply what they learned about simple machines and pushes and pulls to sport activities. Give each student or small group the Pushes & Pulls with Simple Machines Recording Sheet and 1 set of cards made from Pushes and Pulls with Simple Machine Cards (copied on cardstock and laminated). Students will take turns picking a card, writing it on the recording sheet, and determining whether it would use a push, pull or both.

Extensions:

  • Give students opportunities to create their own list of simple machines that would use a push or a pull or both.
  • Play charades with different types of activities, and have students determine whether that activity would use a push, pull or both.
  • Give each student a kitchen tool/ simple machine. Students should trace the simple machine on 9” x 12” white art paper and create their own “bird” including naming the bird. This art activity stems from reading the book Ice Cream Cone Coot and Other Rare Birds. Read the story, The 3 Pigs and the Scientific Wolf by Mary Fetzner. Have students summarize the story and give examples of simple machines the wolf used to try to capture the three little pigs. Other activities are included at the back of the story.

Family Connections:

Assignments to do with Parents:

  • Have students make a list of simple machines they find at home.
  • Have students determine which simple machine they would be.
  • Give students opportunities to play outside games, determine what simple machines were used if any, and decide what pushes or pulls are used to play the games.

Assessment Plan:

  • Formative assessment includes observation, teacher asking questions, and reading what students recorded about simple machines in science journals.
  • Observation of students sorting Simple Machine Cards: Examples of Levers, Examples of Inclined Planes, Examples of Wedges, Examples of Pulleys, Examples of Screws, and Examples of Wheel
  • Pushes & Pulls with Simple Machines Recording Sheet
  • Simple Machines and Work Recording Sheet

Author:
CYNTHIA PRICE

Created Date :
Mar 27 2011 11:26 AM

 20295 
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